X-rays

X-rays are commonly used in veterinary medicine to investigate disease. X-rays are a type of energy radiating in waves throughout space and are a special form of radiaton called electromagnetic radiation. Other forms of electromagnetic radiation include radiowaves, microwaves, infrared light, visible light, ultraviolet light and gamma rays.

X-rays are present throughout the universe passing through space but are only present in very low quantities surrounding us as we go about our daily duties on the surface of planet Earth. However, we knew nothing about them until Wilhelm Roentgen discovered their existence in a laboratory in Germany in 1895.  When he discovered them however, he very quickly recognised their huge potential in the field of medicine. X-rays would for the first time in the history of the human race, allow mankind to look inside the human body and indeed animal bodies without having to cut them open! It was this discovery that resulted in Roentgen being awarded the first Nobel Prize for Physics in 1901.

We are all now familiar with the use of x-rays in human and veterinary medicine. Hospitals and veterinary surgeries use x-rays daily to help diagnose disease. They can be used to diagnose fractures of bone, cancer or pneumonia in the lung, to investigate heart disease and causes of abdominal pain for example. In addition nowadays some human and veterinary hospitals use other forms of imaging including ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) as part of their radiology or diagnostic imaging departments.

Care has to be taken when x-rays are used. Many people are familiar with the use of lead gowns when an x-ray is being taken for example. This is to protect parts of the body that are not ebing imaged from being exposed to the x-rays themselves. The risk is miniscule because the dose of x-rays from an x-ray procedure in a hospital or verterinary surgery is tiny. But there is no point is taking risks!

The reason that x-rays are potentially harmful is that they have the ability to ionise cells or atoms that they pass through. This means that they have enough energy to knock an electron out of the atom or cell (a bit like a billard being hit by the white ball) thereby damaging killing it. This is only of significant risk if the dose of x-rays is high. Indeed this harmful property is put to very good use in both human and veterinary medicine in the form of radiation therapy. This is where x-rays and sometimes gamma rays, are focused carfully on a particular area and used to kill tumour cell so helping to treat and potentially cure cancer.

In veterinary medicine, x-rays are used commonly as the first step in diagnosing disease of bone such as arthritis, trauma, cancer, congenital and developmental abnormalities and metabolic bone disease.  As far as nasal, orbital, spine, skull and brain disease is concerned, CT and MRI are more and more commonly being used as the primary investigative tool.

Examples of such bone disease include arthritis or degenerative joint disease, osteomyelitis (inflammation or infection of the bone and bone marrow), fractures, or dislocations, osteosarcoma, chondrosarcoma, osteochondritis dissecans (OCD), elbow dysplasia (ununited anconeal process, fragmented medial coronoid process, distal humeral OCD, elbow incongruency), incomplete ossification of the humeral condyles (IOHC), ununited medial humeral epicondyle, retained ulnar cartilage core, hip dysplasia, panosteitis, nutritional or renal secondary hyperparathyroidism, metaphyseal osteopathy, hypertrophic osteopathy and craniomandibular osteopathy.

In the chest, x-rays are frequently  used in evaluating the lung to check for diseases such as cancer, pneumonia, pulmonary oedema (“fluid on the lung”) or haemorrhage, lungworm and collapse or torsion of the lung lobes.  Pneumothorax (free air) and pleural effusion (free fluid) can also be assessed. The outline of the diaphragm can be checked for a diaphragmatic hernia. The size and shape of the heart can be evaluated and secondary lung congestion assessed. Ultrasound is also commonly used in the investigation of the heart (echocardiography) and sometimes the chest.

In the abdomen, the presence of free air or free fluid can also be assessed and the size, shape, number, marginatiion, location and opacity of some abdominal organs checked. Increasingly, ultrasound is being used in the primary   investigation of abdominal disease.